Is MDC signalling allowable on MURS Radios?
I have read over many times GMRS, HAM, FRS, and MURS documents. I know MDC Signalling which is used on Motorola Products is prohibited from use on FRS and GMRS. I havent found anything on the Multi Use Radio Service (MURS) though saying you cannot use MDC 1200 (- or +) signalling on MURS un licensed freqs.
Of course certain restrictions apply like cannot exceed 2 watt output and no repeater, and no antenna exceeding 20 ft high. But does anyone here know for a fact, or work for the FCC (so they can assure me), that MDC signalling is not allowed on the free VHF unlicensed MURS channels?
I am GMRS/HAM certified though planned to use a MURS channel for my small business within the store/property. I know it is also prohibited to run on carrier mode using MURS and DPL/PL must be used and not interferring with other users in area.
I know the factory 2watt Motorolas for MURS use a cheap chirp at end of transmission for user hearing. So basically, would the MDC signal tone (just for that purpose, not a PTT ID system) be legal or illegal to use on MURS?
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47 CFR 95.1307 "Permissible communications" states:
(a) MURS stations may transmit voice or data signals as permitted in this subpart.
(b) A MURS station may transmit any emission type listed in Sec. 95.631(j) of this chapter.
(c) MURS frequencies may be used for remote control and telemetering functions. MURS transmitters may not be operated in the continuous carrier transmit mode.
(d) MURS users shall take reasonable precautions to avoid causing harmful interference. This includes monitoring the transmitting frequency for communications in progress and such other measures as may be necessary to minimize the potential for causing interference.
47 CFR 95.631(j) states:
(j) A MURS transmitter must transmit only emission types A1D, A2B, A2D, A3E, F2B, F1D, F2D, F3E, G3E. Emission types A3E, F3E and G3E include selective calling or tone-operated squelch tones to establish or continue voice communications. MURS transmitters are prohibited from transmitting in the continuous carrier mode.
Those alphanumeric emission designators are defined in 47 CFR 2.201. F1D and F2D stand for frequency modulation of a single channel containing quantized or digital information without the use of a modulating sub-carrier (F1D) or with the use of a modulating sub-carrier (F2D), excluding time-division multiplex, for data transmission, telemetry, or telecommand. While I’ll let others debate the finer points of whether MDC-1200 is F1D or F2D (see http://batboard.batlabs.com/viewtopic.php?f=1&t=54757 ), assuming MDC-1200 is either F1D or F2D, then MDC-1200 should comply with 95.631(j) unless there is some other limitation on MURS of which I’m not aware or the FCC has some other interpretation, provided the transmission is not made using a "continuous carrier mode." You’ll note that someone in the discussion on batlabs.com mentions Riley Hollingsworth K4ZDH of the FCC. You might want to check to see what his thoughts are on MDC over MURS.
You can find more information on MDC signaling here: http://en.wikipedia.org/wiki/MDC-1200